Drop test assembly and attitude angle and angular velocity simulation method for drop test

Abstract

The application provides a drop test assembly and a method for simulating attitude deflection angle and angular velocity of drop test, which first adopts three-point suspension of a test piece by a sling, and obtains the angular velocity of the test piece by gravity acceleration through a delay control unlocking method to unlock one of the slings; then uses a test piece attitude and angular velocity simulation parameter calculation method to obtain initial state parameters, delay control waiting time parameters and limit protection lock length parameters; according to the delay control unlocking method flow, the timing unlocking of the suspension cable release device and the overall suspension system release device is realized, and finally the drop test considering the test piece attitude deflection angle and angular velocity is realized; in addition, the limit protection cable is set and the limit protection lock length parameters are calculated to avoid the risk of test piece overturning in the delay control unlocking.

Description

Technical Field

[0001] This invention belongs to the field of spacecraft structural mechanics testing, specifically, it relates to a drop test component and a method for simulating attitude deflection angle and angular velocity in drop tests, and more particularly to a drop test component and a method for simulating attitude deflection angle and angular velocity in drop tests of large spacecraft. Background Technology

[0002] Developing reusable launch vehicle technology is of great significance for high-quality and low-cost access to space. A reliable landing buffer system design is essential for the successful recovery of vertical takeoff and landing reusable launch vehicles. The landing buffer system needs to provide sufficient landing support area for the first stage of the rocket and possess retractable, deployable, and locking capabilities. It must resist, absorb, and disperse the enormous impact energy during rocket landing, while preventing instability issues such as tilting and tumbling. Due to the extremely harsh service load environment faced by the landing buffer system, its structure and oil / gas buffer devices are at high risk of structural fracture, structural fatigue, seal failure, and connection failure. Therefore, ground drop tests will be a crucial part of the development of reusable launch vehicles. By simulating landing conditions, potential risks and design flaws in the landing buffer system can be fully identified, supporting the verification of new technologies and materials.

[0003] For drop testing technology, which is mainly applied to aircraft landing gear and landing systems for extraterrestrial probes, the relevant existing technologies currently include:

[0004] (1) A five-degree-of-freedom full-aircraft drop test aircraft attitude follow-up control device (patent document CN103631266A); This patent document discloses a five-degree-of-freedom full-aircraft drop test aircraft attitude follow-up control device; The follow-up control device includes pulleys, load-bearing columns, tension ropes, slide cylinders, and column supports. Among them, four load-bearing columns are symmetrically arranged in two rows on both sides of the test aircraft and are fixed by column supports. Pulleys are provided on the top of the four load-bearing columns and on the ground between the four load-bearing columns. At the same time, a movable slide cylinder is provided in the middle of each load-bearing column. The test aircraft wing is connected to the slide cylinder by tension ropes through ground pulleys and pulleys at the top of the load-bearing columns. The landing gear is directly connected horizontally to the slide cylinder on the load-bearing columns through tension ropes.

[0005] (2) General Aircraft Landing Gear Drop Vibration Test Platform (Patent Document CN117288413A) This patent document discloses a general aircraft landing gear drop vibration test platform, which consists of a support, a collision platform, a traction system, a magnetic attraction device, a specimen mounting frame, a power supply system, a lifting device, a signal acquisition system, and a control system. The aircraft landing gear to be tested is mounted on the specimen mounting frame and connected to it. The specimen mounting frame is magnetically attracted below the magnetic attraction device. The traction system accelerates the movement along the slide rail on the support, driving the specimen mounting frame and the aircraft landing gear to accelerate. When the detection speed of the signal acquisition system reaches the threshold, the magnetic attraction device is de-energized, causing the specimen mounting frame and the aircraft landing gear to perform a projectile motion to simulate the motion conditions during the landing of the aircraft and restore the actual force state of the landing gear when it lands, so as to conduct the test.

[0006] (3) Aircraft Attitude Adjustment Device and Drop Test System (Patent Document CN109131932A) This patent document discloses an aircraft attitude adjustment device and a drop test system. The adjustment device includes: a support frame, fixedly connected to the aircraft; a first adjustment component, movably disposed on the support frame along a first direction; a second adjustment component, movably disposed on the support frame along a second direction and connected to the first adjustment component; and an electromagnetic latch, movably disposed on the second adjustment component along a second direction. The test system includes the above-mentioned adjustment device and a force measuring platform. By changing the position of the aircraft lifting point, the change in the position of the lifting point relative to the aircraft's center of gravity can equivalently change the aircraft's pitch angle and roll angle to achieve aircraft attitude adjustment.

[0007] (4) A device for simulating the directional speed of a dual-wheel landing gear in a full-aircraft drop test (Patent document CN117141744A) This patent document discloses a device for simulating the directional speed of a dual-wheel landing gear in a full-aircraft drop test, including a rotating device, landing gear wheels and two sets of photoelectric switches. The rotating device is installed on the main body of the aircraft and connected to the landing gear wheels. The landing gear wheels include the nose landing gear wheel and the main landing gear wheel. By setting a first rotating device and a second rotating device, the present invention realizes the rotation of the nose landing gear wheel and the main landing gear wheel in the air, thereby conducting a directional speed simulation test of a full-aircraft drop test, which is not affected by external forces and improves the data accuracy and precision of the directional speed simulation test.

[0008] (5) A method and related equipment for determining the load on a reusable rocket outrigger (Patent document CN117592247A) This patent document discloses a method and related equipment for determining the load on a reusable rocket outrigger. The method includes: acquiring strain data corresponding to a preset number of strain gauges, wherein the strain gauges are attached to a preset position on the target outrigger; determining measured information corresponding to the preset position based on the strain data and the physical parameters of the target outrigger, wherein the measured information includes measured information of cross-sectional axial force and measured information of bending moment; acquiring simulation information corresponding to the preset position through a rigid-flexible coupling dynamic model, wherein the simulation information includes simulated information of cross-sectional axial force and simulated information of bending moment; adjusting the rigid-flexible coupling dynamic model until the information error between the measured information and the simulation information is less than a preset error, thereby obtaining a target simulation model; and acquiring load information of the target outrigger under different working conditions based on the target simulation model. The technical solution has the following shortcomings: Attitude deflection angle and angular velocity simulation is very difficult for simulating large-scale flight results. Compared with the drop test of aircraft landing gear, the landing load of an aircraft is much lower than that of a rocket because the wings can continuously provide lift at the moment of landing. For example, the landing load of the Y-7 is 230kN, while the landing load of a current 4m-class reusable rocket will exceed 500kN. In the drop test, when the rocket landing buffer system reaches the predetermined initial attitude and velocity, it needs to be released instantly. The large-scale impact load can easily cause the test system to overturn.

[0009] (6) A drop test device and method (patent document CN113049207A), which discloses a drop test device and method, but can only simulate the vertical drop speed of the test piece and the wheel speed, and cannot simulate the deflection angle of the overall posture of the test piece and the overall rotational speed of the test piece. Summary of the Invention

[0010] To address the shortcomings of existing technologies, the purpose of this invention is to provide a drop test assembly and a method for simulating the attitude deflection angle and angular velocity of drop tests.

[0011] The drop test assembly provided by the present invention includes: a test piece, three suspension cables, an overall suspension system release device, and a suspension cable release device; the three suspension cables are respectively a first suspension cable, a second suspension cable, and a third suspension cable;

[0012] In the initial state of the drop test, the test specimen is suspended by the three suspension cables. The connection points of the first cable, the second cable, and the third cable to the test specimen are the connection points of the first test specimen, the second test specimen, and the third test specimen, respectively. The three suspension cables converge upwards at point O and are connected to the release device of the overall suspension system. The suspension release device is installed in the middle of the first cable.

[0013] Preferably, the connection points of the first test piece, the second test piece, and the third test piece are located on the same cross section of the test piece, forming an equilateral triangle, with the centroid of the triangle coinciding with the centroid G of the test piece;

[0014] The first sling is longer than the second and third slings, so that the plane in which triangle ABC is located forms an angle θ0 with the horizontal plane, which is the initial attitude deflection angle of the test piece.

[0015] The initial attitude deflection angle θ0 of the test piece is determined based on the required attitude deflection angle θ of the test piece when it is unlocked and separated from the overall suspension system release device. t And the test piece rotates and accelerates to the required angular velocity ω. t The difference between the angles rotated is calculated; a suspension release device is installed in the middle of the first sling, which shortens and tightens the first sling to form a limit protection cable that is not under force in the initial state.

[0016] Preferably, the drop test assembly provided according to the present invention is used for experiments and simulations, including:

[0017] Step S1: Setting the initial state of the test specimen in the drop test;

[0018] Step S2: Simulation of the specimen attitude deflection angle and angular velocity in the drop test;

[0019] Step S3: Execute the delay control unlocking method;

[0020] Step S4: Calculation method for simulated parameters of specimen attitude and angular velocity during drop test;

[0021] Step S5: Execute the anti-overturning method in the attitude deflection angle and angular velocity simulation.

[0022] Preferably, in step S1, in the initial state of the drop test, the test specimen is suspended by three slings and connected to the release device of the overall suspension system; the initial attitude deflection angle of the test specimen is θ0, the value of which is based on the required attitude deflection angle θ of the test specimen when it is unlocked and separated from the release device of the overall suspension system. t

[0023] The test piece is rotated and accelerated to the required angular velocity ω. t The difference between the angles rotated is calculated.

[0024] Preferably, step S2, during the implementation of the drop test, includes:

[0025] Step S21: Unlock the first sling through the suspension release device. The first sling is in a slack state and no longer bears the weight of the test piece. The test piece rotates and accelerates under the action of gravitational acceleration.

[0026] Step S22: When the angular velocity of the test piece's rotational acceleration and the attitude deflection angle reach the required test values ​​ω t and θ t A time-delay control unlocking method is used to unlock the release device of the overall suspension system, allowing the test piece to move at a predetermined angular velocity ω. t and the attitude deflection angle θ of the test piece t During free fall, the test specimen relies on gravitational acceleration to obtain vertical velocity, thus completing the drop test.

[0027] Preferably, step S3 includes:

[0028] Step S31: When the suspension release device is unlocked and separated, event E1 is triggered, the trigger is activated, and the message "The suspension release device has been unlocked and separated" is displayed; then, according to the set waiting time Δt, action E2 is executed after a delay, that is, the overall suspension system release device is unlocked and separated; the message "The suspension system release device has been unlocked and separated" is displayed, and finally the control realizes the simulation of the attitude deflection angle and angular velocity of the test piece;

[0029] E1 represents the trigger event, namely the release device of the suspension cable is unlocked and separated; E2 represents the action to be performed after a delay, namely the release device of the entire suspension system is unlocked and separated.

[0030] Preferably, in step S4, the simulation parameters are obtained based on the moment of inertia of the test system, the energy conservation of potential energy change and rotational energy during the swing of the test piece, and the geometric relationships in the test system. These parameters include the calculation expressions for the initial attitude deflection angle θ0 of the test piece and the waiting time Δt of the delay control:

[0031]

[0032] Where I0 is the moment of inertia of the test system, d is the moment of inertia, m is the mass of the test piece, g is the gravitational acceleration, and θ is the attitude deflection angle of the test piece. t For the required test specimen attitude deflection angle, ω t The required angular velocity.

[0033] Preferably, in step S4, the specific derivation process and calculation expression of the initial attitude deviation angle θ0 of the test piece, the waiting time Δt of the delay control, and the increase in distance Δl between A' and O are as follows (A' represents the position point of point A after the test piece rotates):

[0034] Let the distance from the center of gravity G to point O be d, then the moment of inertia I of the test specimen about point O. O yes:

[0035] I O =I cm +md 2 (1)

[0036] Among them, I cm Let be the moment of inertia of the test specimen about its center of gravity. r is the side length of the equilateral triangle, h is the length of the sling between OC and OB, the subscript cm indicates the moment of inertia calculated about the center of gravity, and the subscript O indicates the moment of inertia calculated about point O.

[0037] After the suspension cable release device is unlocked and separated, the potential energy change ΔU during the swing of the test piece is:

[0038] ΔU=mgd(1-cosθ) (2)

[0039] Where m is the mass of the test piece, g is the gravitational acceleration, and θ is the attitude deflection angle of the test piece. The attitude deflection angle at the beginning of the drop test is θ = θ0.

[0040] Kinetic energy K is represented by rotational energy:

[0041]

[0042] According to the law of conservation of energy:

[0043] K=ΔU (4)

[0044] The expression for calculating angular velocity is obtained as follows:

[0045]

[0046] Based on geometric relationships, l is the initial length of the sling between OA, and the expression for the increase in A'O Δl is as follows:

[0047]

[0048] After simplification, Δl is approximately linearly related to θ:

[0049]

[0050] The required angular velocity ω is based on the test piece. t and attitude deflection angle θ t The subscript t represents the final unlocking state time, and 0 represents the initial state time of the experiment. Substituting into equations (5) and (7), we can obtain:

[0051]

[0052] The delay control waiting time Δt ranges from the initial θ0 to the required attitude deflection angle θ. t Time was derived and calculated by integrating the angular velocity:

[0053]

[0054] Preferably, in step S5, to prevent the test piece from overturning and being damaged due to the suspension cable release device unlocking but the overall suspension system release device failing to unlock effectively, a limiting protective cable is set between the sling and the suspension cable release device. When both the suspension cable release device and the overall suspension system release device can unlock normally according to the timing requirements, there is no suspension tension between them, which will not affect the simulation of the tilt angle and angular velocity of the test piece. However, when the suspension cable release device unlocks but the overall suspension system release device fails to unlock effectively, and the distance between them exceeds the limit requirement, the limiting protective cable will tighten during this period to provide suspension force and prevent the test piece from overturning.

[0055] According to a reusable launch vehicle provided by the present invention, the attitude deflection angle and angular velocity simulation method of the drop test described in the present invention are used to simulate the drop test.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] 1. This invention uses a three-point suspension method with slings and a time-delay control unlocking method to effectively and conveniently simulate the attitude deflection angle and angular velocity of the test specimen.

[0058] 2. This invention avoids the risk of test specimen overturning during delayed control unlocking by setting a limit protection cable;

[0059] 3. This invention suspends the test piece as a whole and delays the unlocking at multiple separation unlocking points, so that the test piece forms an attitude deflection angle and angular velocity when it falls, thereby effectively simulating the complex landing attitude of a rocket and proposing a quantitative calculation method. In order to meet the simulation requirements of rocket attitude deflection angle and angular velocity values, the control parameters in the test scheme can be quantitatively designed, including suspension length and separation unlocking delay time. Attached Figure Description

[0060] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0061] Figure 1 This is a schematic diagram of the initial state of the attitude deflection angle and angular velocity simulation in the drop test of this invention.

[0062] Figure 2 This is a schematic diagram of the final unlocked state simulated by the attitude deflection angle and angular velocity in the drop test of this invention.

[0063] Figure 3 This is a schematic diagram of the delay control unlocking method of the present invention.

[0064] Figure 4 This is a schematic diagram of the geometric relationship of the test system of the present invention.

[0065] Figure 5This is a schematic diagram of the limit protection for the drop test of the present invention.

[0066] The diagram shows:

[0067]

[0068] Detailed Implementation

[0069] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0070] like Figures 1 to 5 As shown, this embodiment of the invention provides a drop test assembly, which includes: a test piece 1, three suspension cables (a first suspension cable 2, a second suspension cable 3, and a third suspension cable 4), an overall suspension system release device 5, a suspension cable release device 6, and a limiting protection cable 7. In the initial state of the drop test, the test piece 1 is suspended by the three suspension cables. The connection points of the first suspension cable 2, the second suspension cable 3, and the third suspension cable 4 to the test piece 1 are respectively the first test piece connection point A, the second test piece connection point B, and the third test piece connection point C. The three suspension cables converge upwards at point O and are connected to the overall suspension system release device 5, as shown. Figure 1 As shown. The first test piece connection point A, the second test piece connection point B, and the third test piece connection point C are located on the same cross-section of test piece 1, forming an equilateral triangle, with the centroid of the triangle coinciding with the centroid G of test piece 1. The first sling 2 is longer than the second sling 3 and the third sling 4, such that the plane containing triangle ABC forms an angle θ0 with the horizontal plane, which is the initial attitude deflection angle of test piece 1. Furthermore, the initial attitude deflection angle θ0 of test piece 1 is determined according to the required attitude deflection angle θ of test piece 1 when the overall suspension system release device 5 unlocks and separates. t And the test piece rotates and accelerates to the required angular velocity ω. t The difference between the angles rotated is calculated; a suspension release device 6 is installed in the middle of the first sling 2, which shortens the sling 2 and tightens it to form a limit protection cable 7 that is not under force in the initial state.

[0071] This invention also provides a method for simulating attitude deflection angle and angular velocity in drop tests, which involves conducting experiments and simulations on the drop test assembly provided by this invention, including:

[0072] Step S1: Setting the initial state of the test specimen in the drop test;

[0073] Step S2: Simulation of the specimen attitude deflection angle and angular velocity in the drop test;

[0074] Step S3: Execute the delay control unlocking method;

[0075] Step S4: Calculation method for simulated parameters of specimen attitude and angular velocity during drop test;

[0076] Step S5: Execute the anti-overturning method in the attitude deflection angle and angular velocity simulation.

[0077] Further, in step S1, in the initial state of the drop test, the test specimen 1 is suspended by three slings (first sling 2, second sling 3, and third sling 4) and connected to the overall suspension system release device 5. The initial attitude deflection angle of the test specimen 1 is θ0, the value of which is based on the required attitude deflection angle θ of the test specimen 1 when it is unlocked and separated from the overall suspension system release device 5. t And the test piece 1 rotates and accelerates to the required angular velocity ω. t The difference between the angles rotated is calculated.

[0078] Furthermore, in step S2, the implementation process of the drop test includes:

[0079] Step S21: Unlock the first sling 2 through the suspension release device 6. The first sling 2 is in a slack state and no longer bears the weight of the test piece 1. The test piece 1 rotates and accelerates under the action of gravitational acceleration.

[0080] Step S22: When the angular velocity of the rotational acceleration of test piece 1 and the attitude deflection angle reach the required test values ​​ω t and θ t A time-delay control unlocking method is used to unlock the overall suspension system release device 5, causing the test piece 1 to move at a predetermined angular velocity ω. t and the attitude deflection angle θ of test piece 1 t Free fall, the test piece relies on the acceleration of gravity to obtain vertical velocity, and finally completes the drop test;

[0081] Further, step S3 includes:

[0082] Step S31: When the suspension release device 6 is unlocked and separated, event E1 is triggered, the trigger is activated, and the message "The suspension release device has been unlocked and separated" is displayed; then, according to the set waiting time Δt, the E2 action is executed after a delay, that is, the overall suspension system release device is unlocked and separated; the message "The suspension system release device has been unlocked and separated" is displayed, and finally the control realizes the simulation of the attitude deflection angle and angular velocity of the test piece;

[0083] E1 represents the trigger event, namely the release device 6 of the suspension cable is unlocked and separated; E2 represents the action to be performed after a delay, namely the release device 5 of the overall suspension system is unlocked and separated.

[0084] Further, in step S4, the simulation parameters are obtained based on the moment of inertia of the test system, the energy conservation of potential energy change and rotational energy during the swing of the test piece, and the geometric relationships in the test system. These parameters include the calculation expressions for the initial attitude deflection angle θ0 of the test piece and the waiting time Δt for the delay control:

[0085]

[0086] Where I0 is the moment of inertia of the test system, d is the moment of inertia, m is the mass of the test piece, g is the gravitational acceleration, and θ is the attitude deflection angle of the test piece. t For the required test specimen attitude deflection angle, ω t The required angular velocity;

[0087] More specifically, the derivation process and calculation expression of the initial attitude deviation angle θ0 of test piece 1, the waiting time Δt for delay control, and the increase in distance Δl between A' and O are as follows (A' represents the position point of point A after the test piece rotates):

[0088] Let the distance from the center of gravity G to point O be d, then the moment of inertia I of the test specimen about point O. O yes:

[0089] I O =I cm +md 2 (1)

[0090] Among them, I cm Let be the moment of inertia of test piece 1 about its center of gravity. r is the side length of the equilateral triangle, h is the length of the sling between OC and OB, the subscript cm indicates the moment of inertia calculated about the center of gravity, and the subscript O indicates the moment of inertia calculated about point O. Figure 4 As shown.

[0091] After the suspension cable release device is unlocked and separated, the potential energy change ΔU during the swing of the test piece is:

[0092] ΔU=mgd(1-cosθ) (2)

[0093] Where m is the mass of the test specimen, g is the gravitational acceleration, and θ is the attitude deflection angle of the test specimen. The attitude deflection angle at the beginning of the drop test is θ = θ0.

[0094] Kinetic energy K is represented by rotational energy:

[0095]

[0096] According to the law of conservation of energy:

[0097] K=ΔU (4)

[0098] The expression for calculating angular velocity is obtained as follows:

[0099]

[0100] Based on geometric relationships, l is the initial length of the sling between OA, and the expression for the increase in A'O Δl is as follows:

[0101]

[0102] After simplification, Δl is approximately linearly related to θ:

[0103]

[0104] The required angular velocity ω is based on the test piece. t and attitude deflection angle θ t The subscript t represents the final unlocking state time, and 0 represents the initial state time of the experiment. Substituting into equations (5) and (7), we can obtain:

[0105]

[0106] The delay control waiting time Δt ranges from the initial θ0 to the required attitude deflection angle θ. t Time was derived and calculated by integrating the angular velocity:

[0107]

[0108] Furthermore, in step S5, to prevent the test specimen 1 from overturning and being damaged due to the suspension cable release device 6 unlocking while the overall suspension system release device 5 fails to unlock effectively, a limiting protective cable 7 is installed between the sling and the suspension cable release device 6. Thus, when both the suspension cable release device 6 and the overall suspension system release device 5 unlock normally according to the timing requirements, there is no suspension tension between them, meaning it will not affect the simulation of the test specimen's tilt angle and angular velocity. However, when the suspension cable release device 6 unlocks but the overall suspension system release device 5 fails to unlock effectively, and the distance between them exceeds the limit requirement, the limiting protective cable 7 will tighten during this period, providing suspension force to prevent the test specimen 1 from overturning.

[0109] More specifically, the attitude deflection angle and angular velocity simulation method described in this embodiment of the invention is based on the following principle: First, a test specimen is suspended at three points using slings. One sling is then unlocked using a time-delay control unlocking method, allowing the test specimen to obtain angular velocity due to gravitational acceleration. Then, the initial state parameters, the waiting time parameters for time-delay control, and the length parameters of the limit protection lock are obtained using the test specimen attitude and angular velocity simulation parameter calculation method for drop test. Following the time-delay control unlocking method, the timing unlocking of the sling release device and the overall suspension system release device is realized. Finally, a drop test considering the attitude deflection angle and angular velocity of the test specimen is achieved.

[0110] The present invention also provides an attitude deflection angle and angular velocity simulation system for large aircraft drop tests. The attitude deflection angle and angular velocity simulation system for large aircraft drop tests can be implemented by executing the process steps of the attitude deflection angle and angular velocity simulation method for large aircraft drop tests. That is, those skilled in the art can understand the attitude deflection angle and angular velocity simulation method for large aircraft drop tests as a preferred embodiment of the attitude deflection angle and angular velocity simulation system for large aircraft drop tests.

[0111] The attitude deflection angle and angular velocity simulation system for large aircraft drop tests provided by embodiments of the present invention includes:

[0112] Module M1: Initial state settings for the test specimen during drop test;

[0113] Module M2: Simulation of specimen attitude deflection angle and angular velocity in drop test;

[0114] Module M3: Executes the delay control unlocking method flow;

[0115] Module M4: Calculation method for simulated parameters of specimen attitude and angular velocity during drop tests;

[0116] Module M5: Implements anti-tipping methods in attitude deflection angle and angular velocity simulation.

[0117] Furthermore, in module M1, in the initial state of the drop test, the test specimen 1 is suspended by three cables (first cable 2, second cable 3, and third cable 4) and connected to the overall suspension system release device 5. The initial attitude deflection angle of the test specimen 1 is θ0, the value of which is based on the required attitude deflection angle θ of the test specimen 1 when it is unlocked and separated from the overall suspension system release device 5. t And the test piece 1 rotates and accelerates to the required angular velocity ω. t The difference between the angles rotated is calculated.

[0118] Furthermore, in module M2, the process of conducting the drop test includes:

[0119] Module M21: The first sling 2 is unlocked by the suspension release device 6. The first sling 2 is in a slack state and no longer bears the weight of the test piece 1. The test piece 1 rotates and accelerates under the action of gravitational acceleration.

[0120] Module M22: When the angular velocity and attitude deflection angle of the test piece 1 during rotational acceleration reach the required test values ​​ω t and θ t A time-delay control unlocking method is used to unlock the overall suspension system release device 5, causing the test piece 1 to move at a predetermined angular velocity ω. t and the attitude deflection angle θ of test piece 1 t Free fall, the test piece relies on the acceleration of gravity to obtain vertical velocity, and finally completes the drop test;

[0121] Furthermore, the module M3 includes:

[0122] Module M31: When the suspension release device 6 is unlocked and separated, event E1 is triggered, activating the trigger and displaying the message "The suspension release device has been unlocked and separated"; then, according to the set waiting time Δt, after a delay, action E2 is executed, that is, the overall suspension system release device is unlocked and separated; the message "The suspension system release device has been unlocked and separated" is displayed; finally, the control realizes the simulation of the test piece's attitude deflection angle and angular velocity.

[0123] E1 represents the trigger event, namely the release device 6 of the suspension cable is unlocked and separated; E2 represents the action to be performed after a delay, namely the release device 5 of the overall suspension system is unlocked and separated.

[0124] Furthermore, in module M4, the simulation parameters are obtained based on the moment of inertia of the test system, the energy conservation of potential energy change and rotational energy during the swing of the test piece, and the geometric relationships in the test system. These parameters include the calculation expressions for the initial attitude deflection angle θ0 of the test piece and the waiting time Δt for delay control.

[0125]

[0126] Where I0 is the moment of inertia of the test system, d is the moment of inertia, m is the mass of the test piece, g is the gravitational acceleration, and θ is the attitude deflection angle of the test piece. t For the required test specimen attitude deflection angle, ω t The required angular velocity;

[0127] More specifically, the derivation process and calculation expression of the initial attitude deviation angle θ0 of test piece 1, the waiting time Δt for delay control, and the increase in distance Δl between A' and O are as follows (A' represents the position point of point A after the test piece rotates):

[0128] Let the distance from the center of gravity G to point O be d, then the moment of inertia I of the test specimen about point O. Oyes:

[0129] I O =I cm +md 2 (1)

[0130] Among them, I cm Let be the moment of inertia of test piece 1 about its center of gravity. r is the side length of the equilateral triangle, h is the length of the sling between OC and OB, the subscript cm indicates the moment of inertia calculated about the center of gravity, and the subscript O indicates the moment of inertia calculated about point O. Figure 4 As shown.

[0131] After the suspension cable release device is unlocked and separated, the potential energy change ΔU during the swing of the test piece is:

[0132] ΔU=mgd(1-cosθ) (2)

[0133] Where m is the mass of the test specimen, g is the gravitational acceleration, and θ is the attitude deflection angle of the test specimen. The attitude deflection angle at the beginning of the drop test is θ = θ0.

[0134] Kinetic energy K is represented by rotational energy:

[0135]

[0136] According to the law of conservation of energy:

[0137] K=ΔU (4)

[0138] The expression for calculating angular velocity is obtained as follows:

[0139]

[0140] Based on geometric relationships, l is the initial length of the sling between OA, and the expression for the increase in A'O Δl is as follows:

[0141]

[0142] After simplification, Δl is approximately linearly related to θ:

[0143]

[0144] The required angular velocity ω is based on the test piece. t and attitude deflection angle θ t The subscript t represents the final unlocking state time, and 0 represents the initial state time of the experiment. Substituting into equations (5) and (7), we can obtain:

[0145]

[0146] The delay control waiting time Δt ranges from the initial θ0 to the required attitude deflection angle θ.t Time was derived and calculated by integrating the angular velocity:

[0147]

[0148] Furthermore, in module M5, to prevent the test specimen 1 from overturning and being damaged due to the suspension release device 6 unlocking while the overall suspension system release device 5 fails to unlock effectively, a limiting protection cable 7 is installed between the sling and the suspension release device 6. Thus, when both the suspension release device 6 and the overall suspension system release device 5 unlock normally according to the timing requirements, there is no suspension tension between them, meaning it will not affect the simulation of the test specimen's tilt angle and angular velocity. However, when the suspension release device 6 unlocks but the overall suspension system release device 5 fails to unlock effectively, and the distance between them exceeds the limit requirement, the limiting protection cable 7 will tighten during this period, providing suspension force to prevent the test specimen 1 from overturning.

[0149] In summary, this invention provides a drop test component and a method for simulating attitude deflection angle and angular velocity in drop tests of large aircraft. First, a test specimen is suspended at three points using slings. A delayed-control unlocking method is used to unlock one of the slings, allowing the specimen to acquire angular velocity based on gravitational acceleration. Then, using a drop test specimen attitude and angular velocity simulation parameter calculation method, initial state parameters, delayed-control waiting time parameters, and limit protection lock length parameters are obtained. Following the delayed-control unlocking method, the timing of the sling release device and the overall suspension system release device is sequentially unlocked. Finally, a drop test considering the specimen's attitude deflection angle and angular velocity is achieved. Furthermore, by setting a limit protection cable and calculating the limit protection lock length parameter, the risk of specimen overturning during delayed-control unlocking is avoided.

[0150] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0151] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0152] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for simulating attitude deflection angle and angular velocity in a drop test, characterized in that, Simulation was performed using drop-shock test components. The drop test assembly includes: a test piece (1), three suspension cables, an overall suspension system release device (5), and a suspension cable release device (6); the three suspension cables are a first suspension cable (2), a second suspension cable (3), and a third suspension cable (4); In the initial state of the drop test, the test piece (1) is suspended by the three suspension cables. The connection points of the first suspension cable (2), the second suspension cable (3), and the third suspension cable (4) to the test piece (1) are the first test piece connection point A, the second test piece connection point B, and the third test piece connection point C, respectively. The three suspension cables converge upward at point O and are connected to the overall suspension system release device (5). The suspension cable release device (6) is installed in the middle of the first suspension cable (2). The first test piece connection point A, the second test piece connection point B, and the third test piece connection point C are located on the same cross section of the test piece (1), forming an equilateral triangle, and the centroid of the triangle coincides with the centroid G of the test piece (1); The first sling (2) is longer than the second sling (3) and the third sling (4), such that the plane containing triangle ABC is perpendicular to the horizontal plane. θ The included angle of 0, that is, the attitude deviation angle of the test piece in the initial state (1); Initial state of the test piece (1) attitude deflection angle θ The value 0 is determined by the required attitude deflection angle of the test piece (1) when it is unlocked and separated from the release device (5) of the overall suspension system. θ t The test piece is rotated and accelerated to the required angular velocity. ω t The difference between the angles rotated is calculated; a suspension release device (6) is installed in the middle of the first sling (2), which shortens and tightens the first sling (2) to form a limit protection cable (7) that is not under force in the initial state. The method for simulating attitude deflection angle and angular velocity in the drop test includes: Step S1: Setting the initial state of the test specimen in the drop test; Step S2: Simulation of the specimen attitude deflection angle and angular velocity in the drop test; Step S3: Execute the delay control unlocking method; Step S4: Calculation method for simulated parameters of specimen attitude deflection angle and angular velocity during drop test; Step S5: Execute the anti-overturning method in the attitude deflection angle and angular velocity simulation; In step S1, in the initial state of the drop test, the test piece (1) is suspended by three slings and connected to the release device (5) of the overall suspension system; the attitude angle of the test piece (1) in the initial state is θ0, the value of which is based on the attitude angle θ required for the test piece (1) when it is unlocked and separated by the release device (5) of the overall suspension system. t The test piece (1) is rotated and accelerated to the required angular velocity. ω t The difference between the angles rotated is calculated. Step S2, during the implementation of the drop test, includes: Step S21: Unlock the first sling (2) through the suspension release device (6). The first sling (2) is in a relaxed state and no longer bears the weight of the test piece (1). The test piece (1) rotates and accelerates under the action of gravitational acceleration. Step S22: When the angular velocity of the test piece (1) is accelerated by rotation The attitude deflection angle met the test requirements. ω t and θ t The delay control unlocking method is used to unlock the overall suspension system release device (5), so that the test piece (1) moves at a predetermined angular velocity. ω t and the attitude deflection angle of the test piece (1) θ t Free fall, the test piece relies on the acceleration of gravity to obtain vertical velocity, and finally completes the drop test; Step S3 includes: Step S31: When the suspension cable release device (6) unlocks and separates, event E1 is triggered, activating the trigger and displaying the message "The suspension cable release device has been unlocked and separated"; then, according to the set waiting time Δ t After a delay, the E2 action is executed, which unlocks and separates the overall suspension system release device; the message "Suspension system release device has been unlocked and separated" is displayed, and finally the control realizes the simulation of the test piece's attitude deflection angle and angular velocity; E1 represents the trigger event, namely the release device (6) of the suspension cable is unlocked and separated; E2 represents the action to be performed after the delay, namely the release device (5) of the overall suspension system is unlocked and separated. In step S4, the simulation parameters, including the initial attitude deflection angle of the test piece, are derived based on the moment of inertia of the test system, the energy conservation of potential energy change and rotational energy during the swing of the test piece, and the geometric relationships in the test system. θ 0. Delay control waiting time Δ t The calculation expression: in, Let the moment of inertia of the test system be _____. d The distance of the centroid G from point O is... m For the quality of the test specimen, g It is the acceleration due to gravity. θ The attitude deflection angle of the test specimen. θ t To achieve the required attitude deflection angle of the test specimen, ω t To achieve the required angular velocity, Angular velocity, .

2. The method for simulating attitude deflection angle and angular velocity in a drop test according to claim 1, characterized in that, In step S5, to prevent the test piece (1) from overturning and being damaged due to the suspension release device (6) being unlocked but the overall suspension system release device (5) failing to unlock effectively, a limiting protection cable (7) is formed between the first sling (2) and the suspension release device (6). When both the suspension release device (6) and the overall suspension system release device (5) can unlock normally according to the timing requirements, the limiting protection cable (7) has no suspension pressure, which means it will not affect the simulation of the test piece's attitude deflection angle and angular velocity. When the suspension release device (6) is unlocked but the overall suspension system release device (5) fails to unlock effectively, the limiting protection cable (7) will be tightened to provide suspension force and prevent the test piece (1) from overturning.

3. A reusable launch vehicle, characterized in that, The drop test was simulated using the attitude deflection angle and angular velocity simulation method according to any one of claims 1 or 2.

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